The present invention relates to nitrogen containing grafted ethylene copolymers useful as multifunctional viscosity index (V.I.) improver additives, e.g., viscosity index improvers-dispersants, for oleaginous compositions, particularly fuel oils and lubricating oils, methods for preparing said grafted ethylene copolymers, and to oleaginous compositions containing these nitrogen containing grafted copolymers. More specifically the instant invention relates to a copolymer of ethylene with other alpha-olefins as a backbone, said copolymer comprised of segmented copolymer chains with compositions which are intramolecularly heterogeneous and intermolecularly homogeneous, grafted with ethylenically unsaturated carboxylic acid material and reacted with amido-amine. The additives of the instant invention provide oleaginous compositions, particularly lubricating oil compositions, exhibiting improved low temperature viscometric properties compared to conventional nitrogen containing grafted ethylene-alpha-olefin copolymers.
The concept of derivatizing V.I. improving high molecular weight ethylene and alpha-olefin copolymers with acid moieties such as maleic anhydride, followed by reaction with an amine or an amine and a carboxylic acid component to form a V.I.-dispersant oil additive is known and is disclosed, inter alia, in the following patents:
U.S. Pat. No. 3,316,177 teaches ethylene copolymers such as ethylene-propylene, or ethylenepropylene-diene, which are heated to elevated temperatures in the presence of oxygen so as to oxidize the polymer and cause its reaction with maleic anhydride which is present during the oxidation. The resulting polymer can then be reacted with alkylene polyamines.
U.S. Pat. No. 3,326,804 teaches reacting ethylene copolymers with oxygen or ozone, to form a hydroperoxidized polymer, which is grafted with maleic anhydride followed by reaction with polyalkylene polyamines.
U.S. Pat. No. 4,089,794 teaches grafting the ethylene copolymer with maleic anhydride using peroxide in a lubricating oil solution, wherein the grafting is preferably carried out under nitrogen, followed by reaction with polyamine.
U.S. Pat. No. 4,137,185 teaches reacting C.sub.1 to C.sub.30 mono carboxylic acid anhydrides, and dicarboxylic anhydrides, such as acetic anhydride, succinic anhydride, etc. with an ethylene copolymer reacted with maleic anhydride and a polyalkylene polyamine to inhibit cross linking and viscosity increase due to further reaction of any primary amine groups which were initially unreacted.
U.S. Pat. No. 4,144,181 is similar to U.S. Pat. No. 4,137,185 in that it teaches using a sulfonic acid to inactivate the remaining primary amine groups when a maleic anhydride grafted ethylene-propylene copolymer is reacted with a polyamine.
U.S. Pat. No. 4,169,063 reacts an ethylene copolymer in the absence of oxygen and chlorine at temperatures of 150.degree. to 250.degree. C. with maleic anhydride followed by reaction with polyamine.
A number of prior disclosures teach avoiding the use of polyamine having two primary amine groups to thereby reduce cross-linking problems which become more of a problem as the number of amine moieties added to the polymer molecule is increased in order to increase dispersancy.
German Published Application No. P3025274.5 teaches an ethylene copolymer reacted with maleic anhydride in oil using a long chain alkyl hetero or oxygen containing amine.
U.S. Pat. No. 4,132,661 grafts ethylene copolymer, using peroxide and/or air blowing, with maleic anhydride and then reacts with primary-tertiary diamine.
U.S. Pat. No. 4,160,739 teaches an ethylene copolymer which is grafted, using a free radical technique, with alternating maleic anhydride and a second polymerizable monomer such as methacrylic acid, which materials are reacted with an amine having a single primary, or a single secondary, amine group.
U.S. Pat. No. 4,171,273 reacts an ethylene copolymer with maleic anhydride in the presence of a free radical initiator and then with mixtures of C.sub.4 to C.sub.12 n-alcohol and amine such as N-aminopropylmorpholine or dimethylamino propyl amine to form a V.I.-dispersant-pour depressant additive.
U.S. Pat. No. 4,219,432 teaches maleic anhydride grafted ethylene copolymer reacted with a mixture of an amine having only one primary group together with a second amine having two or more primary groups.
German published application No. 2753569.9 shows an ethylene copolymer reacted with maleic anhydride by a free-radical technique and then reacted with an amine having a single primary group.
German published application No. 2845288 grafts maleic anhydride on an ethylene-propylene copolymer by thermal grafting at high temperatures and then reacts with amine having one primary group.
French published application No. 2423530 grafts maleic anhydride on an ethylene-propylene copolymer with maleic anhydride at 150.degree. to 210.degree. C. followed by reaction with an amine having one primary or secondary group.
The early patents such as U.S. Pat. Nos. 3,316,177 and 3,326,804 taught the general concept of grafting an ethylene-propylene copolymer with maleic anhydride and then reacting with a polyalkylene polyamine such as polyethylene amines. Subsequently, U.S. Pat. No. 4,089,794 was directed to using an oil solution for free radical peroxide grafting the ethylene copolymer with maleic anhydride and then reaction with the polyamine. This concept had the advantage that by using oil, the entire reaction could be carried out in an oil solution to form an oil concentrate, which is the commercial form in which such additives are sold. This was an advantage over using a volatile solvent for the reactions, which has to be subsequently removed and replaced by oil to form a concentrate. Subsequently, in operating at higher polyamine levels in order to further increase the dispersing effect, increased problems occurred with the unreacted amine groups corss-linking and thereby causing viscosity increase of the oil concentrate during storage and subsequent formation of haze and in some instances gelling. Even though one or more moles of the ethylene polyamine was used per mole of maleic anhydride during imide formation, cross-linking became more of a problem as the nitrogen content of the polymers was increased. One solution was to use the polyamines and then to react the remaining primary amino groups with an acid anhydride, preferably acetic anhydride, of U.S. Pat. No. 4,137,185 or the sulfonic acid of U.S. Pat. No. 4,144,181. The cross-linking problem could also be minimized by avoidance of the ethylene polyamines and instead using amines having one primary group which would react with the maleic anhydride while the other amino groups would be tertiary groups which were substantially unreactive. Patents or published applications showing the use of such primary-tertiary amines noted above are U.S. Pat. No. 4,219,432, wherein a part of the polyamine was replaced with a primary-tertiary amine; U.S. Pat. No. 4,132,661; U.S. Pat. No. 4,160,739; U.S. Pat. No. 4,171,273; German No. P2753569.9; German No. 2,845,288; and French No. 2,423,530.
U.S. Pat. No. 4,516,104 and 4,632,769 represented a further improvement over the art in that they permitted the utilization of the generally less expensive polyamines having two primary amine groups, while achieving good dispersancy levels, inhibiting cross-linking and allowing initiator, e.g., peroxide, grafting in oil.
U.S. Pat. No. 4,517,104 discloses polymeric viscosity index (V.I.) improver-dispersant additives for petroleum oils, particularly lubricating oils, comprising a copolymer of ethylene with one or more C.sub.3 to C.sub.28 alpha-olefins, preferably propylene, which have been grafted with acid moieties, e.g., maleic anhydride, preferably using a free radical initiator in a solvent, preferably lubricating oil, and then reacted with a mixture of a carboxylic acid component, preferably an alkyl succinic anhydride, and a polyamine having two or more primary amine groups. Or the grafted polymer may be reacted with said acid component prereacted with said polyamine to form salts, amides, imides, etc. and then reacted with said grafted olefin polymer. These reactions can permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking or gelling.
U.S. Pat. No. 4,632,769 discloses oil soluble viscosity improving ethylene copolymers such as copolymers of ethylene and propylene, reacted or grafted with ethylenically unsaturated carboxylic acid moieties, preferably maleic anhydride moieties, and then reacted with polyamines having two or more primary amine groups and a C.sub.22 to C.sub.28 olefin carboxylic acid component, preferably alkylene polyamine and alkenyl succinic anhydride, respectively. These reactions can permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking or gelling.
While the additives disclosed in U.S. Pat. Nos. 4,517,104 and 4,632,769 provide quite useful oil compositions there is a need for oil compositions which exhibit better low temperature viscometric properties than those possessed by conventional oil compositions.
U.S. Pat. No. 2,921,085 relates to the preparation of beta-aminopropionamides by reaction of an alkyl amine with an acrylate to form an alkyl aminopropionate and reaction of the latter compound with an amine. The resulting compounds are disclosed to have utility as surface active agents, specifically as emulsifying, wetting, foaming and detergent agents.
U.S. Pat. No. 3,337,609 relates to adducts of hydroxyalkyl alkylene polyamines and acrylates. The resulting adducts are added to polyepoxides to provide compositions which are suitable for use as a barrier coating for polyethylene surfaces, and for additional end uses, such as in molding. In addition, the adducts are disclosed to be useful as catalysts in resin preparation and as corrosion inhibitors in water systems for ferrous metals.
U.S. Pat. No. 3,417,140 relates to the preparation of amido-amine compositions, which are useful as epoxy resin curing agents, by reacting a polyalkylene polyamine and a fatty amine (comprising a mono- or diamine having as one of the substituents on a nitrogen atom a hydrocarbyl radical having 8 to 24 carbon atoms) with an alpha-beta unsaturated carbonylic compound. It is disclosed that this reaction occurs through the Michael addition of an amine group across the unsaturated group of the carbonylic compound and through the condensation of an amine group with the carbonylic group.
U.S. Pat. No. 3,247,163 also relates to curing agents for polyepoxide compositions, which curing agents are prepared by reacting an organic amine and an acrylate.
U.S. Pat. No. 3,445,441 relates to amino-amine polymers characterized by being a reaction product of at least a polyamine and an acrylate type compound, such as methyl or ethyl acrylate, and methyl or ethyl methacrylate. The patent states that the polymers are useful in a wide variety of applications, such as floculating agents, water clarifying additives, corrosion inhibitors in oil and gas wells, and as lube oil additives. The patent further discloses that the polymers may be derivitized, including acylation with monocarboxylic acids and polycarboxylic acids, aliphatic dicarboxylic acids, aromatic dicarboxylic acids, for example, diglycolic, phthalic, succinic, etc., acids.
U.S. Pat. No. 3,903,003 relates to lubricating compositions containing an amido-amine reaction product of a terminally carboxylated isoprene polymer which is formed by reacting a terminally carboxylated substantially completely hydrogenated polyisoprene having an average molecular weight between about 20,000 and 250,000 and a nitrogen compound of the group consisting of polyalkylene amines and hydroxyl polyalkylene amines.
U.S. Pat. No. 4,493,771 relates to scale inhibiting with compounds containing quaternary ammonium and methylene phosphonic acid groups. These compounds are derivatives of polyamines in which the amine hydrogens have been substituted with both methylene phosphonic acid groups or their salts and hydroxypropyl quaternary ammonium halide groups. The patent discloses that any amine that contains reactive amino hydrogens can be utilized, for example, polyglycol amines, amido-amines, oxyacylated amines, and others.
U.S. Pat. No. 4,459,241 contains a similar disclosure to U.S. Pat. No. 4,493,771.
The problem of providing V.I. oil additives exhibiting improved low temperature viscometric properties is addressed in U.S. Pat. No. 4,804,794, which is incorporated herein by reference. U.S. Pat. No. 4,804,794 discloses segmented copolymers of ethylene and at least one other alpha-olefin monomer, each copolymer being intramolecularly heterogeneous and intermolecularly homogeneous and at least one segment of the copolymer, constituting at least 10% of the copolymer's chain, being a crystallizable segment. These copolymers are disclosed as exhibiting good mechanical properties such as good shear stability and as being useful V.I. improvers which provide lubricating oils having highly desirable viscosity and pumpability properties at low temperatures. However, these copolymers are disclosed as being V.I. improvers, and there is no disclosure of grafting said copolymers with an ethylenically unsaturated carboxylic acid material and thereafter reacting these grafted copolymers with amido-amines to provide multifunctional viscosity index improver additives, e.g., viscosity index improverdispersant additives, for oleaginous compositions. Indeed, it was heretofore generally believed that these ethylene copolymers could not be grafted with conventional ethylenically unsaturated grafting materials and thereafter reacted with nitrogen containing compounds such as polyamines without substantially deleteriously or adversely affecting, i.e., broadening, the narrow molecular weight distribution (MWD). It was believed that this deleterious effect upon the narrow MWD would have a concomitant deleterious effect upon the intermolecular homogeneity, microstructure (intramolecular heterogeneity), and, therefore, upon the advantageous low temperature viscometric properties. It has been surprisingly discovered that oleaginous compositions containing ethylene copolymers grafted with ethylenically monounsaturated carboxylic acid material and reacted with an amido-amine to form nitrogen containing grafted ethylene copolymers exhibit better low temperature viscometric properties than those containing conventional nitrogen containing grafted ethylene copolymers. Thus, the multifunctional viscosity index improver additives of the instant invention provide oleaginous compositions, particularly lubricating oil compositions, exhibiting dispersancy and better low temperature viscometric characteristics than conventional multifunctional viscosity index improvers comprised of nitrogen or ester containing grafted conventional ethylene copolymers.